Position of element n Infinite sorted array

Author: ParthDhavan04

InfiniteArray.java

@@ -0,0 +1,45 @@
+/* Given an infinite sorted array. Find position of element in this array */
+
+
+//since it is an infinite array therefore arr.length cannot be used to find end. But we need to find end for binary search. So we take chunks/small sizes of boxes for finding start end range
+
+public class InfiniteArray {
+    public static void main(String[] args) {
+        int[] arr = {3, 5, 7, 9, 10, 90,
+                100, 130, 140, 160, 170};
+        int target = 10;
+        System.out.println(ans(arr, target));
+    }
+    static int ans(int[] arr, int target) {
+        // first find the range
+        // first start with a box of size 2
+        int start = 0;
+        int end = 1;
+
+        // condition for the target to lie in the range
+        while (target > arr[end]) {
+            int temp = end + 1; // this is my new start
+          
+            // double the box value
+            // end = previous end + sizeofbox*2
+            end = end + (end - start + 1) * 2;
+            start = temp;
+        }
+        return binarySearch(arr, target, start, end);
+
+    }
+    static int binarySearch(int[] arr, int target, int start, int end) {
+        while(start <= end) {
+            int mid = start + (end - start) / 2;
+
+            if (target < arr[mid]) {
+                end = mid - 1;
+            } else if (target > arr[mid]) {
+                start = mid + 1;
+            } else {
+                return mid;
+            }
+        }
+        return -1;
+    }
+}